i just finished "Identity of Indiscernibles" by Max Black and I'm a bit confused.
In Max Black's paper, A (the character that asserts that the identity of indiscernibles is true) says to B (the denier) that a world that has things that is radially symmetrical to itself is not verifiably different from a world that does not(this is the part after the famous two-ball example, p.162). Why does A do so? Can't A say there is a difference for the world where there is a pair of things differ from the world with just one of each thing in their relational properties to the copies of themselves? Why does A bite the bullet and claim the two universes are indistinguishable?
thanks to any answers!